Amount Of Particles Research Articles

A study on the production of extracellular vesicles derived from novel immortalized human placental mesenchymal stromal cells

Extracellular vesicles (EVs) are not only involved in cell-to-cell communications but have other functions as “garbage bags”, as bringing nutrients to cells, and as inducing mineral during bone formation and ectopic calcification. These minuscule entities significantly contribute to the regulation of bodily functions. However, the clinical application of EVs faces challenges due to limited production yield and targeting efficiency. In our study, we propose a method for efficiently harvesting EVs utilizing simian virus 40 large T antigen (SV40LT) immortalized human placental chorionic mesenchymal stromal cells (CMSCs). We investigated immortalized placental chorionic mesenchymal stromal cells (imCMSCs), a stromal cell line that surpasses the growth limitations of primary passage cells while retaining phenotypic characteristics and differentiation potential. This development offers the prospect of a consistent, uniform source of EVs, which is essential for regenerative medicine. Our findings indicate that the immortalization process preserves the particle size, quantity and surface marker profiles of EVs, providing a possible approach to produce high-yield EVs suitable for disease diagnosis and treatment.

A comparative Study of the Erosive Wear Caused by Organic and Inorganic Abrasive Particles

In this study, erosion tests were conducted to evaluate the abrasivity of organic particles to produce wear on a material surface with higher hardness. The novelty of this research work was that pistachio shells, which are usually waste that ends up in the garbage, were collected, ground and sieved to obtain a sufficient quantity of pistachio angular particles to be used productively to perform these wear tests. Additionally, sea shells were thought of as an alternative to organic abrasives, and these were ground, sieved and prepared to be able to carry out the testing. The erosion tests conducted based on ASTM G76 and SEM images showed typical wear mechanisms such as high plastic deformation (material displacement) characterized by micro-cutting and micro-ploughing actions, grooves with lifted lips in the edges as pistachio grits employed to run the tests. On the other hand, a conventional abrasive as glass bead particles caused huge craters, broken and smeared flakes, ploughing and circumferential cracks on the AISI 420 stainless steel surfaces. The highest erosion rates were reached as glass beads were employed to run the erosion tests. AFM technique was used to show the surface variations after the erosive impacts. The eroded scars produced by pistachio and sea shells allowed us to remark that the proposed organic abrasives could be used for polishing, surface finishing and cleaning applications on surfaces of mechanical elements that are dirty or rusty. This was due to their low density, which led to low and very superficial erosion damage.

Anisotropic Microparticles with a Controllable Structure via Soap-Free Seeded Emulsion Polymerization.

Anisotropic particles have a wide range of applications in materials science such as emulsion stabilization, oil-water separation, and catalysis due to their asymmetric structure and properties. Nevertheless, designing and synthesizing large quantities of anisotropic particles with controlled morphologies continue to present considerable challenges. In this study, we successfully synthesized anisotropic microspheres using a soap-free seed emulsion polymerization method. This approach combines the benefits of seed emulsion polymerization with emulsion interfacial polymerization. By varying the concentrations of dissolved polymeric monomers, 3-methacryloyloxypropyltrimethoxysilane (MPS), and the initiator of potassium persulfate (KPS), different shapes of bowl, cap, and three-sided concave particles were obtained in surfactant-free aqueous solutions, simplifying the post-treatment process. The cap particles are Janus particles with good emulsion stability to toluene/water emulsions over 30 days. The catalytic degradation of 4-nitrophenol (4-NP) was investigated after loading silver nanoparticles on the surface of the particles by in situ deposition. The anisotropic particles obtained in this work have potential applications in emulsion stabilization and catalysis.

DaedalusData: Exploration, Knowledge Externalization and Labeling of Particles in Medical Manufacturing - A Design Study.

In medical diagnostics of both early disease detection and routine patient care, particle-based contamination of in-vitro diagnostics consumables poses a significant threat to patients. Objective data-driven decision-making on the severity of contamination is key for reducing patient risk, while saving time and cost in quality assessment. Our collaborators introduced us to their quality control process, including particle data acquisition through image recognition, feature extraction, and attributes reflecting the production context of particles. Shortcomings in the current process are limitations in exploring thousands of images, data-driven decision making, and ineffective knowledge externalization. Following the design study methodology, our contributions are a characterization of the problem space and requirements, the development and validation of DaedalusData, a comprehensive discussion of our study's learnings, and a generalizable framework for knowledge externalization. DaedalusData is a visual analytics system that enables domain experts to explore particle contamination patterns, label particles in label alphabets, and externalize knowledge through semi-supervised label-informed data projections. The results of our case study and user study show high usability of DaedalusData and its efficient support of experts in generating comprehensive overviews of thousands of particles, labeling of large quantities of particles, and externalizing knowledge to augment the dataset further. Reflecting on our approach, we discuss insights on dataset augmentation via human knowledge externalization, and on the scalability and trade-offs that come with the adoption of this approach in practice.

Baseline Study of Ultra-Clean Air Change Rate, Number, and Type of Microorganisms and Level of Particles During Trauma Surgery.

Background: The objective of an operating room (OR) ultra-clean ventilation system is to eliminate or reduce the quantity of dust particles and colony-forming units per cubic meter of air (CFU/m3). To achieve this, ultra-clean goal high air change rates per hour are required to reduce the particle load and number of CFU/m3. Aim: To determine the air quality in an ultra-clean OR during surgery, in terms of the number and type of microorganism and quantity of dust particles in order to establish a benchmark. Methods: Number of CFUs and the quantity of dust particles were measured. For measuring the CFUs, sterile extraction hoses were positioned at the incision, the furthest away positioned instrument table, and the periphery. At these locations, air was extracted to determine the quantity of dust particles. Findings: The number of CFU/m3 and particles was on average at wound level ≤1 CFU/m3 resp. 852.679 particles, at instrument table ≤1 CFU/m3 resp. 3.797 particles and in the periphery ≤8 CFU/m3, resp. 4.355 particles. Conclusion: The number of CFUs in the ultra-clean area is below the defined ultra-clean level of ≤10 CFU/m3 for ultra-clean surgery. The quantity of dust particles measured during surgery was higher than the defined ISO 5.

Using Static Multiple Light Scattering to Develop Microplastic-Free Seed Film-Coating Formulations.

Seed film-coatings used for seed treatment often contain microplastics which must be replaced. The objective of this study is to analyze the influence of substitutes (maltodextrin, waxy maize glucose syrup (WMGS), methylcellulose, tragacanth gum (TG), arabic gum (AG), polyvinyl alcohol (PVA), ethoxylated rapeseed oil (ERO)), and xanthan gum as a thickener on the stability of a seed film-coating via Static Multiple Light Scattering (SMLS) technology. The results demonstrate that the incorporation of each polymer results in an increase in the quantity of particles migrating from the supernatant phase, but a concomitant decrease in their sedimentation rate and in the thickness of the supernatant phase (ec). Furthermore, the redispersion capacity (Cd) of the particles in the seed film-coating is also decreased after the introduction of each polymer, potentially due to their adsorption to the particles. The impact of the thickener is contingent upon the specific polymer employed. Its incorporation reduces the number of particles migrating from the supernatant phase and their sedimentation rate for all of the polymers studied except AG and ERO. However, it reduces ec for all seed film-coatings. Depending on the substitutes, thickener incorporation either improves (WMGS, maltodextrin, AG) or deteriorates (TG, PVA, ERO) Cd. The formulation containing tragacanth gum shows a redispersing capacity with Cd ≤ 1. This study introduces a novel analytical criterion, the redispersion capacity Cd, which can be employed to characterize dispersed systems.

Statistical Methods in the Analysis of the Effect of Carbonisate on the Hardness of Epoxy-Resin-Based Composites.

This research concerns the manufacture and characterisation of epoxy composites with the addition of carbonisate, obtained by the pyrolysis of MDF (medium-density fibreboard) furniture board waste. The laminated composites were made by hand lamination, with the carbonisate used as a filler to improve the mechanical properties of the composite. The carbonisate was obtained by the thermal decomposition of MDF waste in an anaerobic environment by pyrolysis, which is an efficient method of waste management and material recycling. The resulting carbonisate was integrated into an epoxy resin matrix to investigate its potential as a reinforcing agent. The article describes a study on the hardness of epoxy-resin-based composites to which carbonisate was added in different fractions and percentages. The aim of the research was to test the possibility of using char as a component in improving the mechanical properties of epoxy composites with a view towards creating a durable recycled material with optimal parameters. As part of the study, a statistical analysis of the results of hardness measurements was carried out to accurately assess the effect of the quantity and size of the carbonate particles on the mechanical properties of the materials. The analysis identified significant differences between samples and verified the repeatability of the results. It was found that the addition of carbonisate to the A0 base sample (without the addition of carbonisate) leads to a significant hardening of the material. This was confirmed by the higher medians of samples A01 (carbonisate 5% with a 0.5 mm fraction), A02 (carbonisate 7.5% with a 0.5 mm fraction), and A03 (carbonisate 5% with a 1.0 mm fraction) compared to the base sample. The most homogeneous hardness was shown in sample A02, with the highest concentration of results and the lowest values of standard deviation and spread. The results indicated that the addition of carbonate significantly increased the hardness of the composite materials, with optimal stability achieved at 7.5% (by weight) of carbonate with a 0.5 mm fraction. The conducted research precisely determined the influence of the amount and characteristics of carbonisate particles on the mechanical properties of the materials, which enables the more effective designing of future composites. The statistical results provide a reliable basis for evaluating the potential applications of these materials in various industrial sectors, such as construction, automotive and aerospace, where high hardness and durability are important.

Aerosols: the ignored problem

One central topic has been criminally neglected in the analysis of the corona pandemic: the role of aerosols in the transmission of viruses. Aerosol medicine had already established before 1990 that even when breathing calmly, tiny aerosol particles are released from the bronchi or lungs. When infected with a respiratory virus, the quantity of exhaled aerosol particles increases by up to three powers of ten, but only in the so-called 'superemitters' (superspreaders). It is not known why only a small proportion of those infected become superemitters.

The Microstructure and Wear Properties of Ni-coated and Agglomerated-Sintered WC-10Ni/316 Composite by Laser Melting Deposition

WC-10Ni particle-reinforced stainless steel matrix composites have potential applications in aerospace, energy engineering, automotive manufacturing, and marine engineering equipment. However, there is currently insufficient research on the integrated manufacturing and comparative analysis of Ni-coated (WC-10Ni)1.5/316 and agglomerated-sintered (WC-10Ni)1.5/316 composites using Laser Melting Deposition (LMD) technology. In this work, the fabrication and examination of the LMDed specimens are conducted to determine the influence of the forming process of particle reinforcement on the microstructure and wear properties of WC-10Ni/316 composites. The microstructure, phase composition, composition distribution, microhardness, and wear resistance of the two composites were comparatively analyzed using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), microhardness tester, X-ray diffraction(XRD), energy-dispersive spectroscopy (EDS), and a reciprocating wear tester. The results indicate that the microstructure of Ni-coated (WC-10Ni)1.5/316 composite specimen contains a higher quantity of undecomposed Ni-coated WC-10Ni particles, with a lower proportion of precipitates, and dendrites predominantly exhibit an elongated dendrite morphology. In contrast, the agglomerated-sintered (WC-10Ni)1.5/316 composite specimen features a greater content of decomposed agglomerated-sintered WC-10Ni particles, a higher content of precipitates, and dendrites mainly present as slender dendrites. Both composites consist of phases such as γ-(Fe, Ni, Cr), WC, W2C, Fe6W6C, M6C, and Cr23C6. The undecomposed WC-10Ni particles and tungsten precipitates significantly enhance the microhardness and wear resistance of the specimen. Specifically, the Ni-coated (WC-10Ni)1.5/316 composite specimen displays a microhardness of 350.2±3.3 HV1.0, with a wear rate of 1.5797±0.0455mg/(N·km). Meanwhile, the Agglomerated-sintered (WC-10Ni)1.5/316 composite specimen reveals an average microhardness of 410.9±6.1 HV1.0 and a wear rate of 0.8057±0.0352mg/(N·km).

Numerical Simulation of the Distribution Patterns of Particle Deposition on the Vertical Wall Behind Near-Wall Heat Source

Near-wall heat sources have a crucial part to play in the process of particle deposition. Thus, this study investigates the impact of the near-wall heat source on the distribution patterns of particle deposition on the vertical wall behind the heat source, taking into account the variability in heat source temperatures and distances from the vertical wall. A model based on the Eulerian–Lagrangian method was established for tracking the motion trajectories of 1000 particles with a density of 1400 kg/m3 and a particle size range of 0.01–10.0 μm. The temperature field, airflow field, and particle deposition distribution in six cases were analyzed. It was shown that the heat source temperature significantly affectis the temperature field, airflow field, and particle deposition distribution on the vertical wall behind the heat source. This study demonstrated that as the temperature rises, the quantity of particles deposited in the upper-right region of the vertical wall decreases more noticeably. The quantity of particles deposited onto the vertical wall is inversely related to the distance between the near-wall heat source and the vertical wall. On one hand, the deposition distribution law serves as a foundation for advancing the technology aimed at removing suspended particles via thermal plumes. On the other hand, it provides critical insights for addressing the challenges associated with harmful particle deposition linked to the attachment effects of thermal plumes.

Host protein PRPS2 interact with the non-structural protein p17 of Avian Reovirus and promote viral replication

Avian reovirus (ARV) is highly prevalent in healthy poultry flocks and has been linked to viral arthritis/tendonitis, dwarf syndrome, chronic respiratory disease, and immunosuppression in avian species, resulting in significant economic losses within the poultry industry. The non-structural protein p17 encoded by ARV induces cellular autophagy and facilitates viral proliferation, playing a pivotal role in viral pathogenesis. To further elucidate the pathogenic mechanism basis of ARV p17 protein function, we employed a yeast two-hybrid system to identify Phosphoribosyl pyrophosphate synthetase 2 (PRPS2) as an interacting host protein with p17. In this study, we validated the interaction between PRPS2 and p17 using laser confocal microscopy, coimmunoprecipitation, and GST-Pulldown assays. Moreover, our findings demonstrate that the C-terminal region of PRPS2 is responsible for its binding to the p17 protein. Intriguingly, ARV infection significantly upregulated PRPS2 expression levels. Additionally, PRPS2 was shown to have a substantial impact on ARV replication; overexpression of PRPS2 increased ARV replication while knockdown of PRPS2 resulted in decreased quantities of ARV particles. Furthermore, our findings suggest that this process involves cellular apoptosis as a potential mechanism underlying these observations. Overall, this research provides valuable insights into elucidating the function of the p17 protein and sheds light on the pathogenic mechanism involving ARV-induced cellular apoptosis while offering novel perspectives for exploring therapeutic targets against ARV.

Characterization of the Elemental Composition of Aerosols Emitted in the Dry Season of the Pantanal Wetland, Brazil

The Brazilian Pantanal region experiences intense biomass burning during the dry season, releasing large quantities of gasses and particles into the atmosphere, which have serious implications on both the climate system and public health. Understanding the dynamics of these emissions is crucial for mitigating the impact on the ecosystem, its functioning, and potential anthropogenic disturbances. This study focused on analyzing emissions in the northern Pantanal during the 2022 drought. Concentrations of fine particulate matter (PM2.5), black carbon (BC), and 25 chemical elements were measured using gravimetry, reflectance analysis, and X-Ray fluorescence, respectively, from samples collected between August and October 2022. The average concentrations of PM2.5 and BC increased approximately 4-fold and 2.5-fold, respectively, compared to averages from a decade ago. Significant increases were also observed in elements such as sulfur (S), potassium (K), iron (Fe), and silicon (Si). The maximum concentrations were comparable to values typical of the southern Amazon, a region known for high deforestation rates and land use changes. Elemental analysis revealed substantial shifts in concentrations, primarily associated with biomass burning (BB) and soil suspension. Additionally, enrichment factor (Ef) analysis showed that lead (Pb) levels, correlated with human activities, were 200 times higher than those found under clean atmospheric conditions.

Optimizing Drug Delivery to the Brain for Breast Metastasis: A Novel Method for Tumor Targeting.

Brain metastases are difficult to treat due to the blood-brain barrier limiting the delivery of therapeutic agents to the brain effectively. Intraventricular drug delivery has not been well studied for intra-axial pathologies. However, our prior work demonstrated that intraventricular drug delivery in a hyperosmolar vehicle showed preferential accumulation of drug within breast cancer tissue compared to surrounding brain parenchyma. The focus of this study was to explore the molecular parameters of intraventricular drug administration that may optimize drug delivery to intra-axial brain metastases. Our hypothesis was that a low molecular weight drug with a high osmolarity solution would increase drug delivery to tumor tissue. We used an intracerebral breast cancer tumor model in adult female nude rats divided into six experimental groups. We examined three iron-labeled dextran molecules (3 kD, 5 kD, and 10 kD) in 337 mOsm/L solution and three different osmolarities of delivery solution (307, 353, and 368 mOsm/L) with 10 kD dextran. 7T magnetic resonance imaging (MRI) was used to analyze dextran distribution at different time points. All animals were sacrificed after two hours, and the quantity of dextran particles was determined by histopathology. Breast cancer tumor cells were successfully implanted in all rats. The MRI quantification of dextran concentration was well corroborated by histopathology. Varying the molecular size of dextran resulted in the smallest molecule reaching peak levels in tumor tissue earlier than the larger molecules, but the larger molecules remained concentrated in tumor tissue for a longer time. Varying the osmolarity of the delivery solution resulted in the preferential accumulation of 10 kD dextran in tumor tissue except for when dextran was delivered in 368 mOsm/L solution where no preferential distribution was seen. Hyperosmolar intraventricular delivery of chemotherapeutic drugs could be effective in preferentially delivering drugs to abnormal tumor tissues.

State primary standard for units of absorbed dose and absorbed dose rate of photon, electron, proton radiation and in carbon ion beams, quantity, fuence, fux density and energy of particles in proton beams and heavy charged particles GET 38-2024

The problem of ensuring the accuracy and traceability of the measurement results of the absorbed dose in carbon ion beams, as well as the measurement results of the amount, fluence, flux density and energy of particles in proton and heavy charged particles beams is considered. Until now, in practice, these values have been measured only by indirect methods. The lack of approved measuring instruments for the quantities under consideration and the metrological traceability of measurement results of these quantities to standards did not allow achieving consistency of measurement methods used in practice and confirming the reliability of the results obtained. To solve this problem, three measuring complexes have been developed and created, which are included in the State Primary Standard of units of absorbed dose and absorbed dose rate of photon, electron, proton radiation and in carbon ion beams, quantity, fluence, flux density and energy of particles in proton and heavy charged particles beams GET 38-2024. The measuring complex for reproducing the unit of absorbed dose in carbon ion beams consists of an adiabatic calorimeter, a thermostating system, a data collection and processing system and a vacuum pumping station. To reproduce the unit of energy of protons and heavy charged particles, a complex has been implemented, which includes a total absorption calorimeter, a data collection and processing system, a vacuum pumping station and a particle count determination system based on the use of a Faraday cup. To reproduce the units of fluence and particle flux density in proton and heavy charged particles beams, a measuring complex has been created containing a Faraday cup, a set of collimators and a low current meter. The schemes, the principles and the results of studies of the metrological characteristics of the developed measuring complexes are described. The results are relevant for the field of radiation therapy and radiation resistance tests of the electronic component base used in the space industry.

Attracting magnetic BDD particles onto Ti/RuO2-IrO2 by using a magnet: A novel 2.5-dimensional electrode for electrochemical oxidation wastewater treatment

Boron-doped diamond (BDD) is a well-known anode material with a high pollutant degradation ability for electrochemical oxidation wastewater treatment. Nevertheless, the cost of production and mechanical strength of BDD membranes remain unsatisfactory. Magnetic BDD particles derived from industrial waste may represent a promising alternative to BDD membranes, although the challenge remains in assembling these particles into a usable electrode. In this study, magnetic BDD particles were attracted to a Ti/RuO2-IrO2 electrode using a magnet, thus constituting a novel 2.5-dimensional (2.5D) electrode. To ascertain the structure-activity relationship of the novel electrode, essential characterizations, multi-physics simulations, pollutant degradation and electrosynthesis experiments were conducted. The results indicate that an appropriate quantity of BDD particles (0.1 g/cm2) can enhance the number of active sites by approximately 20%. A strong synergistic effect was observed between the Ti/RuO2-IrO2 and BDD particles in the degradation of various pollutants, including azo dye, p-benzoquinone, succinic acid and four kinds of real wastewaters, as well as glycerol conversion. The joint active sites on the interface between Ti/RuO2-IrO2 and BDD particles, as well as the inner active sites on BDD particles, have been identified as crucial in the mineralization of pollutants and the generation of value-added products. The optimal amount of BDD particles (0.1 g/cm2) is sufficient to preserve the joint active sites and to maintain an adequate polarization on the BDD particles. Nevertheless, the hybrid feature of the 2.5D electrode is diminished when a greater quantity of BDD particles (0.3 g/cm2) is loaded.

Entrapment behavior of argon bubbles and non-metallic inclusions under combined magnetic fields in slab continuous casting

The entrapment of argon bubbles and non-metallic inclusions under combined applications of electromagnetic braking (EMBr) and electromagnetic stirring (EMS) is receiving increasing attention in slab continuous casting. A Eulerian-Lagrangian model, incorporating Archimedes electromagnetic force, was established to study the entrapment behavior of particles under multi-mode electromagnetic fields. Results showed that the novel EMBr device could enhance the mixing of liquid steel around the nozzle and significantly suppress inclusion entrapment. The optimal magnetic induction intensity ranged from 0.218 T to 0.272 T based on the number of entrapped particles beneath the slab surface. Furthermore, employing appropriate drag force coefficients and considering the Archimedes electromagnetic force were crucial for predicting the quantity and size of entrapment particles. Particles from the nozzle jet experienced a downward electromagnetic force induced by EMBr. EMS tended to drag particles toward the solidified shell, with a more pronounced effect on large-sized particles. More particles were entrapped by the solidified shell in numerical results. Further research should account for Archimedes electromagnetic force in quantitative examination of inclusion entrapment.

Ethylene vinyl acetate/copper sulphide with near-infrared light active shape memory behavior

This thesis presents the preparation of ethylene vinyl acetate (EVA)-based shape memory polymer composites (SMPC) (EVA/CuS) with near-infrared light photo-thermal response. The composites were prepared using EVA as the matrix material and copper sulphide (CuS) particles as the functional phase. The designability of SMPs was considered in the preparation of these composites. The results demonstrated that the incorporation of CuS, as a functional phase, enhanced the cross-linking degree and augmented the shape memory properties of EVA. Additionally, it served as a photo-thermal functional filler, imparting its photo-thermal properties. It can be observed that as the quantity of CuS particles incorporated into the EVA/CuS composite film increases, the photothermal conversion performance of the composite film improves, the shape fixation rate rises, and the rate of recovery of light-responsive shape memory accelerates. The temperature of the composites increased to 116.7°C in 20 s when the CuS addition was 2 wt% and the NIR light intensity was 0.5 W/cm2. At a NIR light intensity of 0.6 W/cm2, the “U” shape of the sample was restored to a straight state in 30 s, and the shape recovery rate reached 100%. In this experiment, optical near-infrared photostimulation-responsive EVA/CuS composites have been successfully prepared. These composites demonstrate the ability to achieve remote control and fast response of EVA shape memory behavior, offering a new avenue for the preparation of photo-responsive EVA-based shape memory materials.

In vitro Evaluation of Titanium Exfoliation during Simulated Surgical Insertion of Dental Implants

ABSTRACT Background: Titanium dental implants are widely used due to their biocompatibility and mechanical properties. However, the potential for titanium particle exfoliation during surgical insertion remains a concern, as it may affect osseointegration and peri-implant health. This study aims to evaluate the extent of titanium exfoliation during simulated surgical insertion of dental implants. Materials and Methods: A total of 30 titanium dental implants were surgically inserted into synthetic bone blocks using a standardized drilling protocol. The procedure was conducted in a controlled laboratory environment to simulate clinical conditions. Titanium particle exfoliation was assessed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) at multiple insertion depths (0 mm, 5 mm, and 10 mm). The quantity of titanium particles was measured and analyzed statistically. Results: The SEM and EDS analyses revealed significant titanium exfoliation at each insertion depth. The mean number of titanium particles detected at 0 mm, 5 mm, and 10 mm depths were 25 ± 5, 45 ± 8, and 60 ± 10 particles per mm2, respectively. There was a statistically significant increase in particle count with increasing depth of insertion (P < 0.01). Conclusion: The findings indicate that titanium exfoliation occurs during the surgical insertion of dental implants and increases with the depth of insertion. This exfoliation could potentially impact peri-implant tissue health and osseointegration. Further clinical studies are necessary to assess the long-term effects of titanium particle exfoliation on implant success.

Scalable Synthesis of Degradable Copolymers Containing α-Lipoic Acid via Miniemulsion Polymerization.

A robust method is described to synthesize degradable copolymers under aqueous miniemulsion conditions using α-lipoic acid as a cheap and scalable building block. Simple formulations of α-lipoic acid (up to 10 mol %), n-butyl acrylate, a surfactant, and a costabilizer generate stable micelles in water with particle sizes <200 nm. The ready availability of these starting materials facilitated performing polymerization reactions at large scales (4 L), yielding 600 g of poly(n-butyl acrylate-stat-α-lipoic acid) latexes that degrade under reducing conditions (250 kg mol-1 → 20 kg mol-1). Substitution of α-lipoic acid with ethyl lipoate further improves the solubility of dithiolane derivatives in n-butyl acrylate, resulting in copolymers that degrade to even lower molecular weights after polymerization and reduction. In summary, this convenient and scalable strategy provides access to large quantities of degradable copolymers and particles using cheap and commercially available starting materials.

Microstructure and mechanical properties of Al2O3/AZ61 Mg alloy surface composite developed using friction stir processing and groove reinforcement filling processes

Abstract In this work, the alumina (Al2O3) particles-reinforced AZ61 magnesium (Mg) alloy surface composite was fabricated using friction stir processing (FSP) and groove reinforcement filling methods. The Mg alloy surface composites were developed with and without the addition of Al2O3 reinforcing particles, and their mechanical performance was compared with each other and with unprocessed base metal (BM). The Al2O3 powder was compressed into a groove of 4.5 mm depth that had been created in AZ61 Mg alloy plates. The volume fraction of Al2O3 powder was increased to 5, 10, and 15 vol.% depending on the width of the groove. Results disclosed that the problem of cluster formation of reinforcing Al2O3 particles was minimized by performing FSP in five number of passes. The ultimate tensile strength (UTS) and hardness of AZ61 Mg alloy were enhanced by 6.07 % and 22.23 % when it was subjected to FSP. This is primarily correlated to the significant refining of grains due to the severe plastic deformation associated with FSP. The 15 vol.%-FSPed Al2O3/AZ61 Mg alloy surface composite showed a higher UTS of 630 MPa and hardness of 300 HV. This is due to the integration of a greater quantity of Al2O3 particles with substantial grain refining.